find-usb-block.sh

#!/bin/sh

PRECHECK=$(ls /dev/disk/by-id/* | grep usb | wc -l)
if [ $PRECHECK -eq 0 ]; then
	echo No USB block devices are connected.
	exit 1
fi

NUMUSBDEVICES=$(ls /dev/disk/by-id/usb* -1 | xargs readlink -f | grep -E '[a-z]+$' | wc -l)
if [ $NUMUSBDEVICES -ne 1 ]; then
	echo $NUMUSBDEVICES USB devices are connected, but it must be only 1 device.
	exit 1
fi

USBDEVICE=$(ls /dev/disk/by-id/usb* -1 | xargs readlink -f | grep -E '[a-z]+$')
echo $USBDEVICE